Columella (gastropod)

The columella is often only clearly visible as a structure when the shell is broken, sliced in half vertically, or viewed as an X-ray image.

[1] The columellar muscle passes underneath the mantle, greatly thickening the body wall, through the foot and is attached at its other end to inner face of the operculum (if present).

The columellar muscles are contracted when the animal needs to withdraw the foot, head, and other soft parts into the shell for protection from drying out, and from predators.

In very large gastropods such as the queen conch (Aliger gigas) once the columellar muscles are cut with a knife, the soft parts of the animal fall out of the shell easily.

Conch fishermen in the Caribbean Sea break a small hole in the spire of the shell, cut the columellar muscles, and harvest the live meat of this species.